The evidence is clear: Africa is experiencing the powerful impact of climate change. Weather patterns are changing, resulting in more droughts and floods, and higher air and water temperatures. Glaciers on the famous Rwenzori mountains, long fabled as the Mountains of the Moon, have shrunk by half since the late 1980s – symbolic of more profound changes taking place.

The effects on people, particularly the poor, are severe. Farmers, pastoralists, fishing communities and town dwellers are vulnerable to changes in water availability and agricultural productivity. As yields drop, people need other sources of income to meet their basic needs. A warmer climate increases the risk of vector-borne diseases such as malaria. Even if the temperature rise can be kept within the 2C band, an additional 40-60 million Africans are likely to be exposed. Economic necessity and competition for resources are already resulting in mass movement of people within countries and across borders, heightened social tension and, in many cases, violence.

The economic implications are enormous. Receipts from agricultural activities, which account for over half the jobs and GDP in many African countries, may decline sharply. And just as national ­revenues are strained, demand for ­public expenditure will increase.

African ministers of finance are meeting in Rwanda next week to craft a response to climate change. They are central to finding a solution, for climate change cannot be treated as a sectoral issue. It is fundamental to the success of economic growth and achievement of the millennium development goals.

The news is not all bad. Climate change opens up opportunities to generate revenue and diversify economies. Projects to reduce greenhouse gas emissions can help rich countries meet carbon offset obligations and generate revenue for entrepreneurs and governments. The clean development mechanism, for example, allows industrialised countries to invest in projects that reduce emissions in developing countries, as an alternative to more expensive emissions reductions in their own countries.

Other schemes offer African countries the chance to benefit from global payments for preservation of forests, which in turn capture carbon and preserve soil, water and life. Indeed, long-term climate change strategies offer a chance for African countries to leapfrog towards efficient renewable technologies.

Effective policies and creative market measures are needed to mobilise investment in renewable power sources such as wind, solar, geothermal and biomass. A resource-efficient green-economy future will require financial support and technology transfer from more advanced economies. This would only be fair. After all, Africa accounts for a mere 2.3% of fossil fuel consumption, though it has 13.8% of the world's population.

But recognition that Africa is least responsible yet most vulnerable is not enough. African governments need to decide how they will adapt their economies and protect their people, and set out what they expect the international community to do to support them.

First, they need to take the lead in crafting development strategies that adapt to climate change as well as invest in infrastructure and clean energy. Shovel-ready projects that bring ­affordable and environmentally sustainable energy to African communities need to be fast-tracked and ­implemented right away.

Second, international organisations, including the African Development Bank, regional economic commissions, UN and Bretton Woods institutions, need the funds, leadership and technical competence to support governments in responding to climate change.

And third, a new global climate deal must address the needs of the least developed countries, most of which are in Africa. It must include binding commitments to ensure access to financial resources and technological knowhow, and reform instruments like the clean development mechanism to ensure they work for Africa. At present, they do not.

The importance of the climate change summit in Copenhagen in December must not be underestimated. The best way for the voice of poor countries to be heard is by promoting a clear position on key issues, including the steps that they and their partners will take to ensure financing of adaptation and appropriate mitigation actions using new and additional sources of swiftly accessible funds – including from carbon markets – and to ensure existing international aid commitments are met.

Africa is not homogeneous. Countries' needs vary. But a strong common position for least developed countries, championed by Africa's heads of state, and anchored with G77 and Chinese partners, must be the cornerstone of a diplomatic and political campaign to secure a fair deal in Copenhagen.

Kofi Annan, a former UN secretary general, chairs the Africa Progress Panel; Lord Stern is IG Patel professor of economics and government at the LSE and led the 2006 Stern review on the economics of climate change